Europeans Look To Provide Solar Event Forecast

In November, a European group will debut its new space weather alert system

The massive ball of hot spitting chaos at the center of our Solar System—the Sun—is so much less tranquil than it looks on the warm spring afternoons coming now to the Northern Hemisphere. This is why researchers at more than half a dozen European space institutes are working to build better tools to forecast the space weather patterns that our nearest star produces in space.

Streams of charged particles known as solar wind are constantly bombarding the Earth, mingling with its magnetic field to form the planet's protective magnetosphere. But periodically the Sun shoots massive amounts of plasma from its fiery surface, threaded with magnetic field lines; this is a coronal mass ejection (CME). It is often accompanied by solar flares many times the size of our planet. These sudden and intense flashes of brightness release massive amounts of magnetic energy built up in the solar atmosphere.

In a “perfect storm” scenario – when a high-powered CME of charged particles slams into Earth at a time when the delicate balance that operators try to maintain in electric power grids is precarious– the resulting damage could take a decade to repair at a cost roughly estimated by the National Academies of Science as high as $1 trillion (AW&ST Jan. 14, p. 49). “Right now we're still not able to forecast solar flares. We know there is a big sunspot, so there's a probability. But when? How big?” says Norma Crosby, a space physicist at the Belgian Institute for Space Aeronomy in suburban Brussels.

Crosby is heading up the group of researchers working on forecasting the space weather impact of geomagnetic and solar energetic particle radiation storms. Next November the group, known as Comesep, will debut its new alert system prototype at European Space Weather Week at the Belgian Royal Academy.

Say you are an astronaut on an extra-vehicular activity and a sudden pulse of energized particles rushes out of the Sun. “There's only 20 minutes to get back inside; that can be a problem,” Crosby says. Closer to home, geomagnetic storms caused by solar wind are major space weather events in the Earth's magnetosphere.

Energetic particles can come whizzing from the Sun at just less than the speed of light in short-duration bursts associated with solar flares. Longer-duration, slower-moving, proton-dominated events occur when particles accelerate from the shock of a CME. These are easier to react to, though they also can pose long-term problems like corrosion.

The Sun is already one of the most closely observed objects in the scientific world. So Comesep—drawing on expertise from advanced, three-dimensional kinematic imaging at the University of Graz in Austria, observatories in Belgium and Croatia, astrophysicists and data analysts in Zagreb, Croatia, and technical universities in Denmark, Greece and the U.K.—is not sending up new space hardware or trying to duplicate ongoing efforts at NASA and the European Space Agency.

Comesep's alert system, rather, relies upon a set of semi-automated, networked software modules. They will deliver probabilities derived from input of near-real-time data and intense historical analysis of solar behavior. One sample system module is Hvar Observatory's so-called drag-based model for predicting terrestrial arrival times and impact speeds of CME. The system will issue automatically updated and recalculated reports based on current conditions.

“We are trying to combine empirical aspects with some relatively basic modeling based on physics and analysis,” says Bojan Vrsnak, an astrophysicist at Hvar in Zagreb. Project organizers are crunching existing historical data on CMEs and solar energetic particles back to the middle of the 19th century, including the giant Carrington Event solar superstorm of 1859 that fried telegraph systems. Comesep analysts have already run calculations on dense data from thousands of samples of strong solar events.

While weather forecasters suffer the same unknown that financial performance forecasters do in the sense that past performance is no guarantee of future results, data nonetheless is a fixed point from which to start, Vrsnak says. “Empirical data is the only thing you can rely on. When you see something happening on the Sun, coming toward the Earth, you can at least know what happens at the Sun and what happens on Earth,” he says.

But, he concedes, “the physics behind these phenomena are highly non-linear. Very similar situations have different outcomes; very small things have outsize influences.”